In the process of scientific research and production, some materials are sensitive to one certain or several active compositions in air, such as oxygen, moisture, carbon dioxide and so on, and thus these research and production should be done in a sealed space filled with inert gases. On the other hand, some materials, which could be harmful to the operators if they are exposed to, should be dealt with in a sealed environment. A glove box, which can be made of metals or plastics, is a typical example of this like device, including a main box body having multiple openings equipped thereon with a view window, an antechamber, glove ports and so on. Operators operate the materials and devices inside the box body through a glove, and the antechamber is used for transferring materials and devices into and out of the glove box.
Existing glove boxes have leakage issues, and it is difficult to keep the respective contents of impurities (such as moisture, oxygen) inside the glove box less than 1 ppm (parts per million), even if the glove box is filled with high purity gas. The contents of moisture and oxygen will rise gradually during the use of the glove box, which makes the contents of moisture and oxygen inside the glove box much higher than what is required.
Specifically, there are following three main reasons why the contents of moisture and oxygen could rise:
1) Air can leak into the glove box through tiny gaps. The interfaces between the main box body and the view window, and between the glove and the glove port are normally sealed with rubber sealing rings, and there always exist tiny gaps around the sealing rings.
2) The oxygen and moisture in air can permeate into the glove box through the glove and the sealing rings. The glove and sealing rings are all rubber products, air can permeate slowly into the glove box through the rubber glove and rubber sealing rings.
3) When materials and devices are transferred into the glove box from outside, a small of amount of moisture and oxygen will be taken into as well. All materials can adsorb oxygen and moisture. Even though those materials have been evacuated in the antechamber before being transferred into the glove box, as shown in FIG. 1, remaining moisture and oxygen in the materials can only be removed very slowly by evacuation alone, and moisture and oxygen will be released gradually after the materials are transferred into the glove box.
And currently, to keep the respective contents of contaminants like oxygen and moisture less than 1 ppm, the glove box is normally equipped with a circulating purification system. As shown in FIG. 1, the system comprises a blower 2 and a purification column 3. The purification column 3 is filled with oxygen and moisture retaining materials. The impurity-containing gas is blown through the purification materials by the blower 2, and the oxygen and moisture are retained. The purified gas is then returned to the glove box. Continuous circulation like that will reduce the respective contents of oxygen and moisture to an equilibrium, namely that, the rate that oxygen and moisture leak into glove box is equal to the removing rate by the purification system. So that, the purity of gas inside the glove box is decided by both of the leak rate of the glove box and the efficiency of the purification system. In a word, the two key technologies in a glove box system are sealing and gas purification.
Currently, the sealing technology used in the glove box is the traditional sealing technology. As shown in FIG. 2, there is one layer of sealing material (such as a sealing ring 5, a sealing stripe, or a sealant) placed between two sealing surfaces. The inner side of the sealing material is ultra-high purity gas, and the outer side of the sealing material is air. Air has oxygen concentration of higher than 200,000 ppm and can easily leak into the glove box through tiny gaps to greatly affect the gas purity inside the box.